典型工况下航空燃气轮机涡轮动叶内部冷却弯道的流动传热机理研究

The increases of aero-engines’ thrust is closely related to turbine inlet total temperature. As a result, many cooling schemes have been widely used in turbine vanes and blades, including internal cooling. Rotation of blades in representative conditions weakens heat transfer in some portions of internal cooling channels comparing to stationary cases and consequently affects the operation safety. In relevant studies, visualized measurements of flow and heat transfer in rotating internal channels are rare. In this proposal, PIV and LCT instruments are loaded on a rotating disk to capture flow features and heat transfer distributions. The coupling mechanism and quantitative relations between flow and heat transfer are studied. The effects of turning vanes on flow and heat transfer in turn regions are studied while the overall heat transfer coefficient is correlated with rotation parameters. In rotating conditions, measuring the flow and heat transfer by PIV and LCT, investigating the effects of turning vanes, and developing quantitative relations are distinguished features of this study. The research is significant to the theoretical and engineering investigations of turbine blade internal cooling. It will build an excellent experimental platform for flow and heat transfer in rotating channels and provides theoretical support for delicate design of blade internal cooling.

航空喷气发动机推力的提升，很大程度上依靠涡轮前温度的不断提高。为此，包括内部冷却在内的多种冷却方式被广泛应用于涡轮动、静叶片。相比静止状态，典型工况下的高速旋转使动叶内部弯道部分区域传热性能明显下降，对其安全运行造成巨大影响。在国内外相关研究中，实现旋转内部通道的流动传热可视化测量，较为少见。本研究拟在旋转盘上搭载PIV和LCT设备，解析动叶片顶部和根部弯道内的的特征流动结构和传热系数分布，阐明两者的耦合机理和定量关联，系统研究弯道导叶对弯道流动传热的影响，发展弯道整体传热性能与旋转参数之间的拟合关系。在航机典型工况的旋转参数条件下，实现流动和传热的可视化测量，发展二者定量关联，探明导叶的作用机理，对燃机涡轮动叶片内部冷却的机理探寻和工程设计具有重要意义，为旋转通道流动传热研究构建了良好的平台与基础，为叶片内部冷却的精细化设计提供了理论支持。

航空发动机和燃气轮机的涡轮前燃气温度，已远高于高温部件材料的耐受极限，冷却技术成为保证其安全工作的必须手段之一。空气冷却叶片具有复杂的内部结构，通过强制对流从叶片内部将进入叶片的热量带走。此外，涡轮动叶内部冷却受到旋转效应的极大影响，不可忽视。从相似理论出发，复现典型工况下静、动叶内部冷却的特征参数，研究特征工况下通道内部传热的根本机制，具有非常重要的理论意义和工程价值。本课题的研究内容包括：1、针对内部冷却常用的多流程通道、柱肋通道和交错肋通道开展了实验研究，获得了通道内的传热与流动特性，并阐明了二者之间的作用机制及相互关联；2、建立了满足航发和50MW重燃动叶内冷特征参数（Re，Ro，Bo）的旋转实验系统，在典型工况下开展了传热可视化测量和CFD模拟，深入分析了科氏力与旋转浮力对动叶内部冷却的影响规律。课题研究针对静止以及旋转状态下的内部冷却开展了系统研究，在传热特性与流动特性的相关性方面提出了独到见解，深入剖析了旋转状态下科氏力与旋转浮力对动叶内部冷却的影响规律，在涡轮叶片内部冷却的机理研究方面取得了显著进展，获得国内外研发单位与同行的关注，为工程研究提供了重要的基础数据。依托项目构建的动叶内部冷却旋转实验平台为后续研究奠定了良好的基础。